images created dynamically do not appear on screen! -> Javascript
I'm trying to do something simple to practice my Javascript (which I learned some recently) and I'm trying to do a game on it (pacman to be precise).
I am trying to build that game board on the browser by creating images dynamically. I've done an array like this:
var images= new Array(25);
for(i=0;i<25;i++)
images[i]= new Array(25);
And, for the game board I used a matrix done with 0 and 1's with 25x25 size (not going to post it here cause is too big and would make my text hard to read) called board.
For the images that I am using right now I have something like this:
var image_empty = new Image();
image_empty.src="Images/empty.jpg";
var image_wall = new Image();
image_wall.src="Images/wall.jpg";
For the initialization function I have something like this:
function drawField()
{
for(i=0;i<board.length;i++)
{
for(j=0;j<board[i].length;j++)
{
if(board[i][j] == 0)
draw(i,j,image_empty);
else if(board[i][j] == 1)
draw(i,j,image_wall);
}
}
}
And for drawing the images themselves I am using this:
function draw(x,y,img)
{
images[x][y] = new Image(22,22);
images[x][y].src = img.src;
images[x][y].style.position = 'absolute';
im开发者_JAVA技巧ages[x][y].style.left = 40+x*22;
images[x][y].style.top = 40+y*22;
}
Every time I run this code nothing appears on the screen. I've tried several times use a load of things but nothing happens. I am saving the pictures (at least I think I am) and still nothing.
Can someone give me some pointers of what could be wrong?
PS: Some people pointed me out using the appendChild method would solve the problem, still, since pacman will be moving around I can't use it to store my images (and I was planning to use the draw function to draw anything).
And btw nor Web Developer plugin or firebug point out errors (the code is correct from their perspective).
Creating an Image in the method you describe doesn't actually display the image. Even putting attributes and styling to make it appear a certain way doesn't add it to the DOM. The advice about append child is correct. For example, if you had:
<div id="main"></div>
and you called
document.getElementById("main").appendChild(images[x][y]);
this would insert the image inside the div. You could do this repeatedly to generate the equivalent of...
<div id="main">
<img src... />
<img src... />
...and so on
</div>
Then, your CSS styling and positioning would work.
There's nothing wrong with your script, but Firebug does display a rendered version of the DOM. As you run the script, you will actually see the HTML tab of Firebug changing with the images you've added to the page.
Also, keep in mind that the DOM must complete loading before you are able to run this. You can accomplish this by doing a simple:
<body onload="drawImages()">
UPDATE: Once you've actually added the 25x25 images, the array still references the elements - they're just now part of the DOM. So, you can change their source via:
images[x][y].src = "newImage.jpg";
If you, for some reason, wanted to remove an image from the board, leaving a gap, you can remove it from the DOM
document.getElementById("main").removeChild(images[x][y]);
or just hide it via CSS.
加载中,请稍侯......
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